ENVI Boiler Controller

Rev. 2.6 (01/27/2015) 1004905953 Software versions 112E, BD71, 49A7, 79F2, 8C51,1043, 9820 ENVI Boiler Controller Advanced User s Guide Installation Date: Harsco Industrial, Patterson-Kelley 155 Burson Street East Stroudsburg, PA 18301 Telephone: (877) 728-5351 Facsimile: (570) 476-7247 www.harscopk.com 2011 Harsco Industrial, Patterson-Kelley Printed: 5/6/2015

1.0 ENVI BOILER CONTROL... 3 1.0 Operation of the ENVI Control... 5 1.1 ENVI control flow chart... 6 1.2 Menu Screen... 7 1.3 Boiler Status Screen... 7 1.4 Information Menu... 8 1.5 Errors Menu... 10 1.6 Program Parameters Menu... 11 1.6.1 Initial Setup of the Control... 11 1.6.2 CH Settings... 12 1.6.2 CH Modes... 14 1.6.3 DHW Settings... 20 1.6.4 DHW Modes... 21 1.6.5 Boiler Settings... 22 1.6.6 OEM SETTINGS... 23 1.7 Configuration Menu:... 23 1.8 CASCADE MENU:... 24 1.8.1 Cascade setup... 24 1.8.2 Control Mode... 24 1.8.3 Master Settings... 25 1.8.4 Master Modes... 26 1.8.5 Cascade Settings... 33 1.9 Service Menu:... 38 2.0 TROUBLESHOOTING... 39 2.0.1 Troubleshooting Table... 39 2.0.1 The Loss of Power... 39 3.0 APPENDIX MODBUS INTERFACE... ERROR! BOOKMARK NOT DEFINED. 3.0.1 Descriptions of MODBUS Register Map... Error! Bookmark not defined. 3.0.2 Boiler State... Error! Bookmark not defined. 3.0.3 Information Byte... Error! Bookmark not defined. 3.0.4 Sequence Byte... Error! Bookmark not defined. 4.0 MODBUS CONFIGURATION... ERROR! BOOKMARK NOT DEFINED. 2

1.0 ENVI BOILER CONTROL The ENVI boiler control consists of 3 components and is an intelligent control system with advanced features such as textbased display, MODBUS communication capabilities, and boiler sequencing. Firing rate and setpoint can be controlled via an external 0-10VDC analog control signal. Errors are date and time stamped, and the control records burner run time at various operating points. A single integral control for temperature control, flame safeguard, firing rate control, blocked flue protection, outdoor air reset, freeze protection, built-in cascade sequencing and more. Throughout this manual and in the ENVI controller the term Hysteresis is used with the meaning of Differential. The ENVI control is capable of accepting building management control via 0-10VDC and MODBUS. Other languages require the use of a Protocol converter which is also available separately from your Patterson-Kelley representative. ENVI APPLICATION Note: The ENVI control is capable of running the boiler on its own without any external control hardware or accessories. However, certain applications warrant the purchase and installation of separate sensors such as: 26-0000-0507 Outdoor air sensor BP-0000-0279 Well and sensor for header and DHW applications ENVI Control 23-0000-0539 Surface mount strap on sensor kit for header or DHW applications ENVI Control BP-0000-0480 Kit, 12 brass thermowell, tank temperature sensor, DHW applications ENVI Control Consult Dual element immersion sensor Factory Optional flow switch: (necessary in some DHW applications) 86-8350-0800 Switch, flow switch Optional aquastat: (necessary in some DHW applications) 10-0000-1209 SW,THERMO,100-200F,HONEYWELL_L6008A1242 23-0000-0233 THERMOWELL, ½ NPT These optional sensors will enhance the performance of the ENVI control and may be necessary to sense the locations needed for some applications to perform properly. 3

This chart represents the temperature/resistance relationship of the 12K ohm thermistor mentioned above. The user should become thoroughly familiar with the operation of the boiler and controls before attempting to make any adjustments. The display panel is used to setup and monitor boiler operation by means of six push buttons; MENU, BACK, ENTER, UP, DOWN, and RESET as shown. There are shortcut functions also associated with these buttons; LIGHT, SET PT, DHW, SVC and CANCEL. The shortcut functions are available only when the default (home) screen is displayed. The four line screen shows boiler operating information on various screens. The display screen is backlit for ease of viewing. The display panel will turn off its backlight after a period of inactivity. Press the BACK button to illuminate the screen. In a cascade system it will be necessary to make control adjustments to every boiler display panel. 4

1.0 OPERATION OF THE ENVI CONTROL Patterson Kelley Boiler Control Version 1.0 [8C51] The control displays the initial boot screen (above) when first powered. The second line of text indicates one of three possible operating configurations: Boiler Control indicates the boiler is set up as a standalone (SA) operation (Factory default) Master Control indicates the boiler is set up as the master in a cascade system. Member 1 (or 2, 3, 4 ) indicates the boiler is set up as a member 1 thru 24 within a cascade system. The value shown on the fourth line of text inside the brackets [8C51] is the software version or code installed on the ENVI boiler controls. There are several versions of the ENVI control. These include 112E, BD71, 49A7, 79F2, 8C51,1043 and 9820. Not all features are available with all versions. Parameters which are only applicable to certain release versions will be designated accordingly. If there is no mention of versions with the parameter, then it is valid for all versions. Feb 17 2013 04:27 Run Power 65% Supply 130 F CH Setpt 146 F The control displays the default (home) screen shown above once boot up is complete. This screen displays; the date, time, boiler status, supply temperature, setpoint temperature, error codes, present operating mode (CH or DHW), CM=cascade master, or CS 01-24=cascade member (also referred to as subordinate or slave). Also, firing rate, FP (freeze protection), CL (cycle limit) and firing rate (Power) may be displayed. Cycle limit & freeze protection settings are explained later in the manual. The control has multiple menu levels to provide set-up and operating information. Navigation through the various menus may be performed using the buttons beneath the display. The function of the buttons may be two-fold as shown below. The shortcut functions are available only when the default (home) screen is displayed. Buttons Function Shortcut Menu Accesses the menu None Back / Light Returns to the previous screen Turns on backlight Enter / Set Pt Accepts the value Accesses CH Settings Up / DHW Increases the value/moves cursor Accesses DHW Settings Down / SVC Decreases the value/moves cursor Accesses Service Mode Reset / Cancel Resets the control Cancels Service Mode 5

1.1 ENVI CONTROL FLOW CHART Note: Parameter ranges in flow chart reference a typical MACH boiler. Parameter ranges will typically be different for a condensing vs. non-condensing boiler such as the Modufire Forced Draft boiler. 6

1.2 MENU SCREEN Menu Standby Information Errors From the main screen, pressing the Standby Information Errors Program Parameters Configuration Cascade Menu Service button provides access to the following sub-menus, shown below: Use the and buttons to scroll to the desired sub menu and the button to select that sub menu. 1.3 BOILER STATUS SCREEN Pressing while in the menu screen returns the boiler status (default) screen described in Section 1.0. The default screen displays the current operating status. A list of possible operating statuses is shown below: Standby boiler waiting for a call for heat or for temperature conditions to require heat Checking Air Switch boiler is in its pre-ignition sequence, verifying the air switch is open prior to proceeding Pre Purge - boiler is beginning the ignition sequence, purging the combustion chamber Ignition - the igniter and gas valve are energized while flame is detected Run flame is established, igniter is de-energized, gas valve is controlled to satisfy heat load Post Purge - boiler has completed the burn sequence and is purging the combustion chamber Post Pumping circulator pump is energized for a specified period to remove residual heat from the boiler Reset the ENVI control has detected an error and locked out the boiler. (DO NOT reset the control without determining and correcting the cause) Blocking (Alarm)-Auto reset- automatic reset lockouts that will self reset when the error condition clears. Locking (Alarm)-Manual reset- manual reset lockouts requiring an operator to press the reset button. If the ignition sequence is started it will be finished. Even if the demand is taken away, the sequence up to the burn state is completed. 7

1.4 INFORMATION MENU Pressing at the INFORMATION menu displays the following information. Information Supply Temp 122 F Return Temp 119 F DHW Temp 14 F Use the and buttons to scroll through the INFORMATION menu. Below is a list of values within the Information screen. This screen is very useful for obtaining values as it displays real time changes. NOTE: Observe the 14 F value in the information screen above. This is the value displayed when the control recognizes an open circuit. This is common when a particular sensor such as the DHW sensor in the example above is not used, but may also occur in the event of an electrically open sensor or sensor circuit. The value displayed in the event of a shorted sensor or sensor circuit is 244 F. The values will be defined further in the following table. 8

Display Description Units Open/Shorted Sensor Indication Supply Temp Outlet / Supply Temperature F 14 F (Open) / 244 F(Shorted) Return Temp Inlet / Return Temperature F 14 F (Open) / 244 F(Shorted) DHW Temp Flue gas Temp HX Temp Outside Temp Domestic Hot Water Temperature at the location of the sensor(field installed) Flue Gas Temperature FD boiler - thermal disc switch breaks the display will indicate 50F Heat Exchanger Temperature available on the MACH line C1500 thru to the C4000 Outside Air Temperature at the location of the sensor (field installed) F 14 F (Open) / 244 F(Shorted) F 50 F (Open) / 280 F(Shorted) F 14 F (Open) / 244 F(Shorted) F -40 F / 176 F CH set Temp Comfort Heat Setpoint Temperature F N/A DHW set Temp Domestic Hot Water Setpoint Temperature F N/A Header Temp Header Temperature at the location of the sensor(field installed) F 244 F / 244 F Flame signal Flame Signal (versions 49A7 and earlier were YES/NO ) μa < 1.7 μa = Flame Not Detected > 1.7 μa = Flame Detected 0-10 Fan speed Fan Speed RPM 0-9999 Analog in Analog Input N/A Not Currently Used Analog out Analog Output N/A Not Currently Used Ignitions Number of Ignitions # 0-99999 Burn Hi HR Hours at High Fire (75% to 100%) HRS 0-99999 Burn MD HR Hours at Medium Fire (45% to 75%) HRS 0-99999 Burn LO HR Hours at Low Fire (20% to 45%) HRS 0-99999 Water press Water Pressure N/A Not Currently Used Water level Water Level Sensor Status Aux LWCO status on FD boilers (if installed) Off/On Low gas press Low Gas Pressure Sensor Status Off/On Air pressure Air Pressure Switch Status Off/On Blocked flue Blocked Flue Switch Status Off/On CH pump Comfort Heat Pump Relay Status Off/On DHW pump Domestic Hot Water Pump Relay Status Off/On Air damper Air Damper Relay Status Off/On Hi gas pressure Hi Gas Pressure Switch Status Off/On 0 = Low Water Cutoff 1 = Low Water Cutoff Detects Water 0 = Low Gas Pressure Switch Open 1 = Low Gas Pressure Switch Closed 0 = Air Pressure Switch Open 1 = Air Pressure Switch Closed 0 = High Exhaust Back Pressure Switch Open 1 = High Exhaust Back Pressure Switch Closed 0 = CH Pump relay Off 1 = CH Pump relay On 0 = DHW Pump relay Off 1 = DHW Pump relay On 0 = Air Damper relay Off 1 = Air Damper relay On 0 = Hi Gas Pressure Switch Open 1 = Hi Gas Pressure Switch Closed 9

1.5 ERRORS MENU Apr 20 2009 14:20 Locking IGNITION FAILURE Err:A01 ERRORS Error 0 A03 Error 1 E01 Error 2 00 Version [8C51] and earlier Versions [1043] and [9820] The ENVI control stores the most recent error. Version 1043 and after store the last 6 errors. These errors may be locking or blocking errors. Pressing while in the menu screen with the cursor on Errors, the ERROR menu displays a list of the last 6 errors as shown.). Pressing and scrolls through the list of errors. Pressing while the cursor is on an error displays several lines of information about the status of the boiler during the error. The error information recorded at the time of the error is shown in the table below. Display Description Units Varies Error Description N/A Error code Error Code Date Date Error Occurred DD-MM-YY Time Time Error Occurred 24:00 Supply Temp Outlet Temperature F Return Temp Inlet Temperature F DHW Temp Domestic Hot Water Temperature F Flue gas Temp Flue Gas Temperature F HX Temp Heat Exchanger Temperature F Outside Temp Outside Air Temperature F Operation Mode Boiler Operation Mode (CH/DHW) F Days run Accumulated Days Runtime # State State at time of error 10

1.6 PROGRAM PARAMETERS MENU 1.6.1 Initial Setup of the Control Press the button, scroll down with the button and select PROGRAM PARAMETERS from the menu by pushing. A screen opens that allows access to the adjustable sub menus. Sub Menu Description CH settings Comfort Heat Settings: Contains settings for specific operation of the comfort heat operation. Contains the different modes of operations available. Holds the outdoor air curve and night setback settings. DHW settings Domestic Hot Water Settings: Contains settings for specific operation of the domestic hot water capabilities. Boiler Settings Boiler Operating Settings: Boiler settings contain the primary settings for the boilers operation. OEM Settings Original Equipment Manufacturer Settings: These setting are non configurable and are for information only. Selecting and editing a sub menu Note: There are three access levels including Service Level 1, Service Level 2, and OEM settings which can be viewed, but cannot be changed in the field. Service Level 1 and Service Level 2 require access codes. Access codes are provided to those individuals who have been properly trained by Harsco Industrial, Patterson-Kelley. CAUTION: Do not change any parameter unless the function of that parameter is thoroughly understood. Improper modification of the parameters may cause the boiler to operate erratically or not at all. 11

1.6.2 CH Settings Parameters CH settings DHW settings Boiler settings While in the PROGRAM PARAMETERS menu, press parameters listed in the table below. Alternatively, pressing at the CH SETTINGS menu to access the comfort heat at the boiler status screen also accesses the CH SETTINGS menu. You can now select any parameter by using the or then pressing. Each parameter can be edited by using the same buttons. Once editing of each parameter is complete save it by pressing. 12

1.6.1.1 Comfort Heat Parameters and Descriptions Function Units Passcode ENVI Text Display Range Level CH Setpoint Comfort Heat Setpoint See Appendix I F User BLR OP (Boiler Operation) Boiler / Pump Run settings 0-3 User Off = 0, On = 1, Off/Pump On = 2, and On/Pump On = 3 0 = Boiler Off, Pump Off 1 = Boiler Auto, Pump Auto 2 = Boiler Off, Pump Continuous 3 = Boiler Auto, Pump Continuous CH Mode Comfort Heat Operation Mode 0-8 SVC1 CH Mode 0 (Setpoint & Stat) See 1.6.3.1 below 0 CH Mode 1 (Outdoor &Stat) See 1.6.3.2 below 1 CH Mode 2 (Outdoor Control) See 1.6.3.3 below 2 CH Mode 3 (Setpoint Control) See 1.6.3.4 below 3 CH Mode 4 (Header & Stat) See 1.6.3.5 below 4 CH Mode 5 (Header & Outdoor & Stat) See 1.6.3.6 below 5 CH Mode 6 (Header & Outdoor) See 1.6.3.7 below 6 CH Mode 7 (Analog Setpoint) See 1.6.3.8 below 7 CH Mode 8 (Analog Firing Rate) See 1.6.3.9 below 8 Hi ODA Temp Maximum Outdoor Air Temperature 40 86 F SVC1 Min ODA SetP Desired setpoint @ Hi ODA Temp See Appendix I F SVC1 Lo ODA Temp Minimum Outdoor Air Temperature -18 59 F SVC1 Max ODA SetP Desired setpoint @ Lo ODA Temp See Appendix I F SVC1 ODA Shutdown Outdoor Air Shutdown Temperature 45 140 F SVC1 Night Setback Hysteresis On Hysteresis Off Reduces CH Set point when enabled by this value 0 58 On Differential (subtract this temperature from the setpoint for start) 0 22 Off Differential (add this temperature to setpoint for off) 0 22 F SVC1 F SVC1 F SVC1 CH Post Pump time Post Pump Time After Burner Shuts Off 0 2550 Sec SVC1 Anti-Cyc Time Restart Time Delay to Prevent Short Cycling 0 2550 Prop Band Proportional Band 0 230 F SVC2 Integral Rate Integral Rate 0 255 Sec SVC2 Der Time Derivative Time 0 255 Sec SVC2 Pwr lmt step (ver. 8C51, 1043, 9820) PMP on demand (ver. 79F2, 8C51, 1043, 9820) Power limit step limits the intervals of rate while driving towards high fire (the lower the value, the slower the step; the higher the value, the faster the step) With the NO selection the boiler pump only runs when there is a need to fire the boiler. With the YES selection the boiler pump runs when an enable signal is present. This is overridden by the BLR OP setting Sec SVC2 0 255 units SVC2 Yes/no SVC2 13

1.6.2 CH Modes There are nine CH Modes (0-8). A more detailed description of each mode is included below. 1.6.2.1 CH Mode = 0 (Setpoint & Stat) Description Setpoint is the desired outlet water supply temperature. Upon heat demand (or enable/disable), the ENVI control fires and modulates the boiler to maintain supply water temperature at the desired CH setpoint. The upper (HYSTERESIS OFF) and lower (HYSTERESIS ON) temperature differentials within CH settings control the temperature at which the burner turns on or off. Example: A boiler with the following parameters (SETPOINT = 160 F, HYSTERESIS OFF = 9 F, HYSTERESIS ON = 10 F) modulates to try to maintain 160 F. If the temperature increases above 169 F (160 F SETPOINT + 9 F HYSTERESIS OFF), the boiler will shut off. Once it shuts off, it will not restart until the temperature drops below 150 F (160 F SETPOINT 10 F HYSTERESIS ON). This is illustrated graphically below. The MIN SETPOINT and MAX SETPOINT parameters within the boiler settings menu limit the setpoint range. See Appendix 3.1 and 3.2 for the default values. 175 170 165 160 155 150 Internal Setpoint Boiler Turns Off Boiler Temperature Boiler Set Point Boiler Turns On 145 0 10 20 30 40 Time CH Mode 0 is recommended for all member boilers in a cascade system with the factory installed enable jumper left in place across LVTB -1 terminals 1 & 2. In the event of failure of the master boiler the members will operate as standalone and control to their CH set points. NOTE: The boiler is enabled by the TB1/LV terminals 1 and 2 (enable/disable) becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. 14

1.6.2.2 CH Mode 1 (ODA & Stat) Outdoor Sensor required. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description In this mode, upon enabling the boiler, setpoint is varied by the outdoor air temperature (ODA). The ENVI control fires and modulates the boiler to maintain outlet water temperature at the setpoint which is determined by the outdoor air temperature and its settings. The upper (HYSTERESIS OFF) and lower (HYSTERESIS ON) temperature differentials control the temperature at which the burner turns on or off. Within CH Settings Hi ODA Temp (Outdoor TMax) 70 F Min ODA SetP (Setpoint TMin) 80 F Low ODA Temp (Outdoor TMin) 20 F Max ODA Setp (Setpoint TMax) 180 F ODA shutdown 68 F (FACTORY SETTINGS SHOWN ABOVE) The Outdoor air sensor reads outdoor air temperature and sends it back to the control. The setpoint is established based on the outdoor air temperature. If the outdoor air temperature is below the (HIGH ODA TEMP), the boiler control begins to maintain a setpoint set by the (MIN ODA SETP). As the outdoor air temperature drops, the setpoint temperature increases until (LO ODA TEMP) is reached by the outdoor air temperature. When the outside air temperature has dropped to meet the (LO ODA TEMP) setting, the setpoint of the boiler will be operating at (MAX ODA SETP). Example: Using the values in the table shown below, the boiler setpoint is 80 F (MIN ODA SETPT) when the outdoor air temperature is 70 F (HI ODA TEMP). As the outdoor air temperature drops, the boiler setpoint increases until the outdoor air temperature is 20 F (LO ODA TEMP). When this occurs, the boiler reaches its maximum setpoint of 180 F (MAX ODA SETPT). If the outdoor air temperature drops further, the boiler setpoint remains at 180 F. NOTE: The boiler is enabled by the TB1/LV terminals 1 and 2 (enable/disable) becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. NOTE: while using CH MODE 1 (ODA&STAT) the ODA shutdown temperature is ignored and does not stop the boiler from running. 15

1.6.2.3 CH Mode 2 (Outdoor Control) Outdoor Sensor required. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description In this mode, setpoint is varied by the outdoor air temperature (ODA). Upon enabling the boiler, the ENVI control fires and modulates the boiler to maintain outlet water temperature at the setpoint determined by the outdoor air temperature and its settings. The upper (HYSTERESIS OFF) and lower (HYSTERESIS ON) temperature differentials control the temperature at which the burner turns on or off. Notes: Reference table and graph in section 1.6.2.2 for example of ODA to Boiler Temp relationship. NOTE: The boiler is enabled when the temperature of the outdoor sensor drops below the ODA SHUTDOWN temperature that can be changed within the CH settings. The TB-1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback function. The night setback setpoint is set within CH settings and reduces the CH set point by its value while enabled. (TB-1/LV terminals 1 and 2 circuit closed) 1.6.2.4 CH Mode 3 (Setpoint Control) Description In this mode, the boiler functions as described in 1.6.2.1, CH Mode 0, except that the external thermostat does not create the call for heat. The closure of TB1/LV terminals 1 and 2 will reduce the CH setpoint by the value of the night setback setting. Example: Using the values, CH SP=180 F and Night Setback=10 F, when TB1/LV terminals 1 and 2 are open the CH setpoint will be 180 F. When TB1/LV terminals 1 and 2 are closed the CH setpoint will be 170 F (180 F -10 F). NOTE: In this mode the boiler will always run to setpoint, since there is no enable circuit closure required. The TB-1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback function. The night setback setpoint is set within CH settings and reduces the CH set point by its value while enabled. (TB-1/LV terminals 1 and 2 circuit closed) 1.6.2.5 CH Mode 4 (Header & Stat) This mode is preferred for the master boiler in a cascade system. A sensor will be needed to sense header temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description In this mode, the boiler functions as described in 1.6.3.1, CH Mode 0, except that the boiler maintains the setpoint temperature where the header sensor is located. NOTE: The boiler is enabled by the TB1/LV terminals 1 and 2 (enable/disable) becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. Note: Placing the master boiler in CH mode 4 on any cascade application will show the header temperature (HDR Supply) on the display in the place of the supply temperature on the third line of text on the master boiler. 16

1.6.2.6 CH Mode 5 (Header & ODA & Stat) Two sensors are required to sense header temperature and outdoor temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description This mode is a combination of CH Mode 1 (ODA & Stat) and CH Mode 4 (Header & Stat). When the boiler is enabled through TB1/LV terminals 1 and 2, the setpoint temperature is maintained at the location of the header sensor based on the ODA reset schedule that is determined from the optional outdoor air sensor. Note: While using CH MODE= 5 (HEADER&ODA&STAT) the ODA shutdown temperature is ignored and does not stop the boiler from running. Note: Reference table and graph in section 1.6.2.2 for example of ODA to Header Temp relationship. NOTE: The boiler is enabled by the TB1/LV terminals 1 and 2 (enable/disable) becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. Note: Placing boiler in CH mode 5 will show the header temperature (HDR Supply) on the display in the place of the supply temperature on the third line of text on the boiler. 1.6.2.7 CH Mode 6 (Header & Outdoor) Two sensors are required to sense header temperature and outdoor temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description This mode is a combination of CH Mode 2 (Outdoor Control) and CH Mode 4 (Header & Stat). The temperature is maintained at the location of the header sensor and the setpoint is based on the ODA reset schedule that is determined from an outdoor air sensor and the night setback feature. The closure of TB1/LV terminals 1 and 2 will reduce the CH setpoint by the value of the night setback setting. Note: In this mode the boiler will always run to setpoint, as there is no enabling needed using this CH mode. Note: Reference table and graph in section 1.6.2.2 for example of ODA to Header Temp relationship. Example: Using the values, CH SP=180 F and Night Setback=10 F, when TB1/LV terminals 1 and 2 are open the CH setpoint will be 180 F. When TB1/LV terminals 1 and 2 are closed the CH setpoint will be 170 F (180 F -10 F). NOTE: The boiler is enabled when the temperature of the outdoor sensor drops below the ODA SHUTDOWN temperature which can be changed within the CH settings. NOTE: The TB1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback function. The night setback setpoint is set within CH settings. 17

1.6.2.8 CH Mode 7 (Analog Control of Setpoint) Description In this mode, an external 0-10 VDC signal controls the setpoint of the boiler. From the factory, the Min Setpoint is set for 42 F for condensing boilers (130 F for non-condensing) and the Max Setpoint is set for 185 F for condensing boilers (220 F for non-condensing). Applying a voltage of at least.5 to 1.5 VDC creates the heat request. Applying 2 VDC sets the boiler setpoint to BOILER MIN SETPOINT. Applying 10 VDC sets the boiler setpoint to BOILER MAX SETPOINT. Applying less than.5 VDC removes the heat request. The Min and Max set points can be adjusted within the boiler settings menu. NOTE: When in analog control mode, enable/disable terminals are non-functional as the boiler is enabled/disabled by applying.5 to 1.5 VDC. Dropping below.5vdc will disable the boiler. Many times the building automation sequence of operation requires an enable/disable circuit; this can be achieved by installing a relay in series with the control signal and opening the contacts to drop voltage to 0VDC thereby disabling the boiler. A normally closed contact will provide fail safe operation. 18

1.6.2.9 CH Mode 8 (Analog Control of Firing Rate) Description In this mode, an external 0-10 VDC signal from the building automation system or some external control determines the firing rate of the boiler. A signal of.5 to 1.5VDC generates a heat request and is required to start the boiler. At 2 VDC the firing rate is 20% and at 10 VDC the firing rate is 100%. Boiler temperature limits and safety features are still active. Although the boiler may be receiving a 10 VDC signal, high fire will not be achieved if certain parameters, such as the boiler maximum temperature, are exceeded. NOTE: When in analog control mode, enable/disable terminals are non-functional as the boiler is enabled/disabled by applying.5 to 1.5 VDC. Dropping below.5vdc will disable the boiler. Many times the building automation sequence of operation requires an enable/disable circuit; this can be achieved by installing a relay in series with the control signal and opening the contacts to drop voltage to 0VDC thereby disabling the boiler. A normally closed contact will provide fail safe operation. 19

1.6.3 DHW Settings Parameters C H settin gs D H W setting s Bo iler settings From the PARAMETERS menu use and to move the cursor to DHW settings then press to access the domestic hot water parameters listed in the table below. Alternatively, pressing (home) screen also accesses the DHW SETTINGS menu. at the default 1.6.3.1 Domestic Hot Water (DHW) Parameters and descriptions ENVI Text Display Function Range Units DHW mode None = 0 Storage & Sensor = 1 Storage & Stat = 2 Plate HX = 3 DHW Type CH/DHW = 0 DHW Priority = 1 3 Way Valve NC = 2 Type of System 0 = No Domestic Hot Water 1 = Storage Tank with Temperature Sensor 2 = Storage Tank with Thermostat 3 = Plate Heat Exchanger w/flow Switch Domestic Hot Water Operation Type 0 = Simultaneous CH and DHW Pumps 1 = DHW pump has priority over CH pump 2 = 1 Boiler Pump: when 3 way valve Normally Closed = DHW when 3 way valve Powered Open = CH 0 3 Passcode Level SVC1 0 2 SVC1 DHW setpoint Setpoint for Domestic Hot Water Output 86 185 F User Tank set Setpoint of Storage Tank (DHW mode 1) 104 162 F User ON different Boiler On Differential 0 36 F SVC1 OFF different Boiler Off Differential 0 36 F SVC1 Tank off dif Tank Off Differential (DHW mode 1) 0 36 F SVC1 Tank on diff Tank On Differential (DHW mode 1) 0 36 F SVC1 Post pmp Time DHW Post Pump Time 0 255 Sec SVC1 Prop band Proportional Band 0 230 F SVC2 Integral RTE Integral Rate 0 255 Sec SVC2 DER time Derivative Time 0 255 Sec SVC2 Pwr lmt step (ver. 8C51, 1043) PMP on demand (ver. 79F2, 8C51, 1043) Priority Time (ver. 79F2, 8C51, 1043) Power limit step limits the intervals of rate while driving towards high fire (the lower the value, the slower the step; the higher the value, the faster the step) With the NO selection the boiler pump only runs when there is a need to fire the boiler. With the YES selection the boiler pump runs when an enable signal is present. This is overridden by the BLR OP setting The maximum amount of time the domestic hot water operation has priority over the comfort heat operation. Timer is reset and starts when the domestic hot water call is enabled. 0 255 units SVC2 No / Yes SVC2 0 255 Min SVC1 20

1.6.4 DHW Modes The DHW system designs that can be accommodated by this control include: DHW mode 1- a storage tank with temperature sensor DHW mode 2- a storage tank with thermostat DHW mode 3- a plate heat exchanger Mach boilers, N Series Modufire boilers, and P-K Sonic Boilers can NOT be used for direct fire DHW applications. These boilers require an isolating heat exchanger between the potable water and the nonpotable boiler loop. D series Modufire boilers and Mach n Roll boiler packages can be used for direct potable water contact in the DHW mode. 1.6.4.1 DHW Mode 1 (Storage & Sensor) Storage Tank with Temperature Sensor Tank Sensor required. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description A storage tank equipped with a temperature sensor is connected to the boiler. The 12K ohm NTC sensor must be wired into the boiler at the DHW sensor terminals (Typically terminals 7 & 8 on TB-1). When the temperature sensor reads that the tank temperature is below the TANK SET parameter by the TANK ON DIFF, the DWH pump circuit is energized and the boiler starts and supplies heat to the tank. The boiler modulates the firing rate to maintain the DHW SETPOINT at the boiler outlet. When the temperature in the tank exceeds the TANK SET parameter by the TANK OFF DIFF, the boiler shuts off the burner and the DHW pump continues to run for a pre-set time (POST PMP TIME). Note: Proper sizing of the storage tank is important to prevent short cycling of the boiler equipment. Check with your authorized Patterson-Kelley Representative for assistance on tank sizing. 1.6.4.2 DHW Mode 2(Storage & Stat) Storage Tank with Thermostat Installer needs to supply a closure device (aquastat, thermostat, flow switch, etc.) to close the DHW Enable circuit (Typically terminals 7 & 8 on TB-1). A list of accessory choices for different applications is shown in section 1.0 on page 3 Description A storage tank equipped with a thermostat is connected to the boiler. When the closure device creates a closed state, the DWH pump circuit is energized and the boiler starts and supplies heat to the tank. The boiler modulates the firing rate to maintain the DHW SETPOINT at the boiler outlet. When the closure device opens, the boiler shuts off the burner and the DHW pump continues to run for a pre-set time (POST PMP TIME). 1.6.4.3 DHW Mode 3 (Plate Heat Exchanger) Heat Exchanger without Storage Installer needs to provide a flow-proving device (flow switch) and a temperature sensor. A list of accessory choices for different applications is shown in section 1.0 on page 3. Description A plate heat exchanger equipped with a DHW flow proving device and a temperature sensor is connected to the boiler. When the flow-proving device closes, it creates a call for heat and the boiler s DHW Pump Contactor terminals close which starts the boiler DHW pump. If the DHW water temperature is below the DHW SETPOINT by the ON DIFFERENTIAL, the boiler fires and supplies heat to the exchanger. The boiler modulates the firing rate to maintain the DHW SETPOINT at the boiler outlet. When the temperature of the boiler water rises above the DHW SETPOINT by the OFF DIFFERENTIAL, the boiler shuts off the burner and the boiler DHW pump continues to run for a pre-set time (POST PMP TIME). When the demand is satisfied, the flow-proving device breaks the call for heat. 21

1.6.5 Boiler Settings Boiler Settings Parameters and descriptions Note: xxxx is dependent upon model of the boiler. ENVI Text Display Function Range Units Passcode Level Boiler type Selects the type of boiler. xxxx xxxx OEM Max Fan Speed (ver. 112E, BD71, Selects the absolute maximum fan speed xxxx RPM SVC2 49A7, 79F2,8C51) CH Max fan (ver. 1043,9820) Selects the maximum allowable boiler CH fan speed. xxxx RPM SVC2 DHW Max fan (ver. 1043,9820) Selects the maximum allowable Domestic Hot Water fan speed. xxxx RPM SVC2 Min fan spd Selects the minimum fan speed. xxxx RPM SVC2 Max setpoint Selects the maximum allowable setpoint xxxx F SVC2 Min setpoint Selects the minimum allowable setpoint xxxx F SVC2 Max Temp Selects the maximum allowable water temperature xxxx F SVC2 Mod back dif MBD offset Lo fire hold Post purge Accel BNR ON Accel BNR OFF Modulation back differential is the differential temperature (Supply temperature Return temperature) allowable before MBD offset begins to modulate the boiler. Modulation Back Differential Offset is a temperature buffer before the boiler drops completely to low fire. Example: 45 F (MBD) + 5 F (MBD Offset) = 50 F at which time the boiler will drop to low fire. Inside of this 5 F range it will step modulate to buffer out an application where the boiler flow may dip just beyond minimum flow for a short period of time. This stabilizes the modulation. Upon ignition, the boiler drives to low fire and holds for this amount of time. This is the amount of time the fan runs after the burner has shut off. Selects the fire rate ramp up speed upon power increase rate (lower=slower) Selects the fire rate ramp down speed upon power decrease rate (lower=slower) 0 64 F SVC2 0 64 F SVC2 0 255 Sec SVC2 0 255 Sec SVC2 1-15 units SVC2 1-15 units SVC2 FP Always enabled (ver. 112E, BD71) FP on/off ( (High settings) (ver. 49A7, 79F2) FP enable (ver. 8C51, 1043) Frost Protection forces the CH pump and burner to run. The Burner will run until the lowest of both supply and return temperature measures above 59 F. HIGH: pump runs at 50 F Burner runs at 42 F LOW: pump runs at 30 F (GLYCOL APPLICATION) Burner runs at 22 F High Low Off F SVC2 Pwr Lmt Step (ver. 79F2) Power limit step limits the intervals of rate while driving towards high fire (the lower the value, the slower the step; the higher the value, the faster the step) 0 255 units SVC2 22

1.6.6 OEM SETTINGS The OEM Settings are password protected by a numerical code and should only be changed by Harsco Industrial, Patterson-Kelley personnel. The only adjustable parameter within OEM settings will be IGN fan speed. To change this parameter use the service level code 2. 1.7 CONFIGURATION MENU: The CONFIGURATION menu is a general menu that allows selection of the display language, date/time, code, F/ C temperature selection and MODBUS address. Menu Errors Program Parameters Configuration Use and to move the cursor to the desired setting then press to access for adjustment. LANGUAGE options include English, French or Spanish. English is the default language. ENVI translation to French or Spanish text has not been developed in any version to date. DATE TIME is factory set at the current date & time in the Eastern time zone at the time of production. The ENVI Display has a long life battery that will store this information. Date & time should be changed to reflect actual time zone, daylight savings time, etc. CODE configuration indicates the display panel software version. F or C configuration allows the user to select Fahrenheit or Celsius. MODBUS ADDRESS configuration allows the user to set the Modbus device identification. Each ENVI control defaults to Modbus address 1. In applications with multiple boilers, it is necessary to assign distinct addresses to each boiler when Modbus communication is used. Section 1.8 will address the cascade menu: There are two separate polarity sensitive communication paths each referred to as a bus. For clarification purposes it is important to understand that the member boilers transfer data to & from the master boiler via the Cascade bus which could be described as an internal bus of the cascade boiler system. The Modbus circuit, which could best be described as an external bus, is a total separate communication path and transfers data to and from all connected boilers, not with each other, but with an external communication system such as a building management system utilizing the Modbus protocol. Communication with other protocols can be established using a protocol converter. Your local Patterson-Kelley Representative can provide information on the Protonode protocol converter that is designed for use with the ENVI control. 23

1.8 CASCADE MENU: 1.8.1 Cascade setup With the power off, you can connect up to 24 boilers into the ENVI Cascade system. Wires are connected from the Cascade terminals (A & B) on the master boiler to the Cascade terminals (A & B) on the member (subordinate or slave) boilers. Connect A to A and B to B. The boilers are connected in series (daisy chain topology) using 18/2 shielded wiring. The wire shield should be grounded on one end only (typically at the master) and the shield connected together and insulated from ground for the rest of the wiring. Member ------------ Master Switch orientation of the board may vary from the picture shown. The result will be a continuous shield grounded on one end only. After making the boiler to boiler connections, select one boiler as the master boiler. Remove the interface cover (if present) and confirm the master/member selector switch is set to the MASTER position (factory set to member position). Ensure that the remaining member boiler switches are set to the MEMBER position. A picture of the master/member selector switch is shown to the left. Note: the MASTER position is away from the blue transformer, while the MEMBER position is towards the blue transformer. The CAUTION! Setting more than one master/member selector switch to the MASTER position may damage the control and cause incorrect operation. Turn the power on. Press button and scroll down to Cascade menu, then press. Then you will see These settings include: CONTROL MODE, MASTER SETTINGS, CASCADE SETTINGS, INFORMATION ERRORS. Cascade Menu Control Mode Master Settings Cascade Settings SA 1.8.2 Control Mode In this menu, the operational mode is selected. Single boiler control SA (stand-alone) as shown in example above Cascade Master - CM Cascade member (subordinate or slave) CS01, CS02, etc. When the boiler is set as master, the cascade address shall be automatically set to 0. When the mode is set as member (slave), the user enters a unique address (1-23) for each boiler. For Example: Boiler 1 (Master) = Cascade address 0, Boiler 2 (Slave) = Cascade address 1, and Boiler 3 (Slave)= Cascade address 2. Note: A boiler selected as a cascade member and not connected to a master or with the master powered down, will result in a NO COMM error. 24

1.8.3 Master Settings These settings can only be accessed on a designated master boiler. The master settings are used in conjunction with the cascade settings to set the system response parameters. These settings are described in more detail below. ENVI Text Display Function Range Units HDR Setpoint Sets the operating temperature at the header 104 194 Pass code Level F SVC2 Power Mode 0 1 SVC2 Power Mode Min Boilers On Power Mode Max Boilers On See Below 1.8.4.1 See Below 1.8.4.2 Header Mode 0 4 SVC2 Header Mode (Header & Stat) Header Mode (Header ODA & Stat) Header Mode (Header & ODA) Header Mode (HDR Setpt Control) Header Mode (HDR Analog Setpt) See Below 1.8.4.3 See Below 1.8.4.4 See Below 1.8.4.5 See Below 1.8.4.6 See Below 1.8.4.7 Hyst Start Blr See Below 1.8.4.8.1 0 36 F SVC2 Hyst Stop Blr See Below 1.8.4.8.2 0 36 F SVC2 Wait Blr Swtch (ver. 112E, BD71, 49A7) Wait Blr Sw on (ver. 79F2, 8C51, 1043, 9820) Wait blr sw pwr (ver. 1043, 9820) Wait Blr sw off (ver. 79F2, 8C51, 1043, 9820) Wait reset time (ver. 8C51, 1043, 9820) Prop Band (Proportional Band) See Below 1.8.4.8.3 1 255 Sec SVC2 See Below 1.8.4.8.4 1 60 Min SVC2 See Below 1.8.4.8.5 0-100% SVC2 See Below 1.8.4.8.6 1 60 Min SVC2 See Below 1.8.4.8.7 Proportional Band 0 1 0 1 2 3 4 On/off SVC2 0 230 F SVC2 Integral Rate Integral Rate 0 255 Sec SVC2 Der Time (Derivative) Derivative Time 0 255 Sec SVC2 Cyc Lmt Incrmnt See Below 1.8.4.8.11 0 50 Min SVC2 Cycl Limit Max See Below 1.8.4.8.12 1 255 Min SVC2 Hys Quic Start See Below 1.8.4.8.13 0 51 F SVC2 25

ENVI Text Display Function Range Units Pass code Level Quic Start Tme See Below 1.8.4.8.13 1 255 Sec SVC2 Hys Quick Stop See Below 1.8.4.8.13 0 51 F SVC2 Quic Stop Time See Below 1.8.4.8.13 1 255 Sec SVC2 LoLoad Waiting See Below 1.8.4.8.14 0 255 Sec SVC2 Start Rotation (ver. 112E, BD71, 49A7, 79F2, 8C51) (ver. 1043, 9820) See Below 1.8.4.8.15 Off On:1-255 On:1-255 Hours Days SVC2 No Blr on Wait See Below 1.8.4.8.16 1 255 Min SVC2 Anti wind up See Below 1.8.4.8.17 On/off SVC2 Lead boiler (ver. 1043, 9820) See Below 1.8.4.8.18 0-23 SVC2 1.8.4 Master Modes (a more detailed description of Power Modes can be found in section 1.8.5.1.1) 1.8.4.1 Power mode = 0, Min Boilers on (typically not the most efficient of the two power mode options) In this mode, when more than two boilers are required to satisfy the load, the last two boilers on will run to 100% as needed. All other boilers will modulate in parallel. This satisfies the load with the minimum amount of boilers firing (Less efficient operation). Example: BLR 1 on 100%, BLR 2 on 100%, as BLR 3 comes on BLR 1 will begin to modulate as BLR 3 runs to 100% when BLR 4 comes on and runs to 100%, BLR 2 will begin to modulate. This sequence will continue until the demand is satisfied. The staging procedure is first on, last off. Power mode = 1, Max Boilers On (Parallel Modulation Default Setting) In this mode, the boilers modulate in parallel based on a signal from the master boiler. This satisfies the load with the necessary number of boilers firing at the lowest fire rate possible resulting in more efficient operation in most cases. The staging procedure is first on, last off. 1.8.4.2 Header Mode = 0, (Header & Stat) Sensor kit required to sense header temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. In this mode, the master boiler controls the operation of all the boilers in the cascade system to maintain a supply temperature where the header sensor is located. Upon an enable signal, from the closure between terminals TB1-1 & TB1-2, the ENVI control on the Master boiler fires and modulates the boilers to maintain header water temperature at the header setpoint. The upper (HYST STOP BLR) and lower (HYST START BLR) temperature differentials in conjunction with other cascade settings control the header temperature at which boilers are added or removed. Example: The Master boiler operates the system to maintain the header setpoint of 160 F. If the temperature increases above 170 F (setpoint 160 F + 10 F HYST STOP BLR), a boiler will shut off. If the temperature decreases below 151 F (setpoint 160 F 9 F HYST START BLR), another boiler will start. NOTE: The cascade system is enabled by the TB1/LV terminals 1 and 2 (enable/disable) on the master boiler becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. 26

1.8.4.3 Header Mode = 1, (Header ODA & Stat) Sensor kits required to sense header & outdoor temperatures. A list of accessory choices for different applications is shown in section 1.0 on page 3. In this mode, the temperature is maintained at the location of the header sensor based on a reset schedule that is determined from an outdoor air sensor. The parameters for changing the reset schedule are in PROGRAM PARAMETERS>CH SETTINGS. An external thermostat wired to the enable/disable circuit controls the heat demand. Upon an enable signal from the closure between terminals TB1-1 & TB1-2, the ENVI control on the Master boiler fires and modulates the boilers to maintain header water temperature at the header setpoint which changes based on outdoor temperature. The upper (HYST STOP BLR) and lower (HYST START BLR) temperature differentials in conjunction with other cascade settings control the header temperature at which boilers are added or removed. NOTE: The outdoor air shutdown does not prevent the boiler from running in this mode. NOTE: The cascade system is enabled by the TB1/LV terminals 1 and 2 (enable/disable) on the master boiler becoming closed or shorted. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. 1.8.4.4 Header Mode = 2, (Header & ODA) Sensor kits required to sense header & outdoor temperatures. A list of accessory choices for different applications is shown in section 1.0 on page 3. In this mode, the temperature is maintained at the location of the header sensor based on a reset schedule that is determined from the outdoor air sensor. The parameters for changing the reset schedule are in PROGRAM PARAMETERS>CH SETTINGS. The boiler is enabled when the temperature of the outdoor sensor drops below the ODA SHUTDOWN temperature that can be changed within the CH settings. NOTE: The TB1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback function. The night setback setpoint is found within CH settings and when enabled, reduces the present set point by its value on closure of the TB1 1&2 circuit. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. 1.8.4.5 Header Mode = 3, (Header Setpoint Control) Sensor kit required to sense header temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. This mode is similar to Header Mode = 0, Header & Stat, described in 1.8.3.3, except there is no external thermostat. The heat demand is continuously maintained and controlled by the header sensor and header setpoint relations. NOTE: The TB1/LV terminals 1 and 2 (enable/disable) operate the switching on/off of the night setback function. The night setback setpoint is found within CH settings and when enabled, reduces the present set point by its value on closure of the TB1 1&2 circuit. This circuit is energized internally. DO NOT APPLY EXTERNAL POWER TO THESE TERMINALS. 27

1.8.4.6 Header Mode = 4, (HDR Analog Setpoint) Sensor kit required to sense header temperature. A list of accessory choices for different applications is shown in section 1.0 on page 3. In this mode, an external 0-10 VDC signal controls the setpoint of the cascade system at the Master boiler. Applying a voltage of at least 0.5 to 1.5VDC creates the heat request. Applying 2 VDC sets the boiler setpoint to Min Setpoint. Applying 10 VDC sets the boiler setpoint to Max Setpoint. Applying less than 0.5 VDC removes the heat request. The BLR Min Setpoint and BLR Max setpoint parameters can be adjusted within boiler settings. The boiler is factory set for min 42⁰F max 180⁰F as displayed in the below graph. NOTICE! When in analog control mode, enable/disable terminals are non-functional. NOTICE! Minimum and maximum setpoints can be changed within Boiler Settings menu. Maximum setpoint Minimum setpoint 1.8.4.7 Additional Master Settings 1.8.4.7.1 Hyst start blr {Hysteresis start boiler} This is the differential below header setpoint at which the master control will initiate the WAIT BOILER SWITCH ON timer to request the next member boiler to run. When the HEADER TEMPERATURE drops below the HEADER SETPOINT minus the HYSTERESIS START BOILER, the WAIT BOILER SWITCH ON timer begins counting down. When the timer expires, the member boiler is requested to fire and the WAIT BOILER SWITCH ON timer resets. 1.8.4.7.2 Hyst stop blr {Hysteresis stop boiler} This is the differential above header setpoint at which the master control will stop a member boiler. When HEADER TEMPERATURE exceeds the HEADER SETPOINT plus the HYSTERESIS STOP BOILER, the WAIT BOILER SWITCH OFF timer begins counting down. When the timer expires, the member boiler is stopped and the WAIT BOILER SWITCH OFF timer resets. 28

1.8.4.7.3 Wait blr swtch {Wait boiler switching} This parameter is the time the master boiler control waits to watch the effect of a change in the number of boilers operating, before making another change. Not available on all revisions. 1.8.4.7.4 Wait blr sw on {Wait boiler switch on} This parameter is the time the master control waits to watch the effect of a change in the number of boilers operating, before making another change ON. See above 1.8.4.8.1 for descriptive example. 1.8.4.7.5 Wait blr sw pwr {Wait boiler switch power} This is the power setting in 0-100% that the master boiler will wait for the last started boiler to achieve before switching on the next boiler in the cascade system. (Set to 100% to deactivate) 1.8.4.7.6 Wait blr sw off {Wait boiler switch off} This parameter is the time the master boiler control waits to watch the effect of a change in the number of boilers operating, before making another change OFF. See above 1.8.4.8.2 for descriptive example. 1.8.4.7.7 Wait reset time In versions 1043 & 9820 this feature allows the WAIT BOILER SWITCH ON timer and WAIT BOILER SWITCH OFF timer to reset back to zero, or pause at that current point whenever a heating cycle is complete. This on/off setting allows the wait time to: ON = resets time for sequence every time a reduction in heat load occurs back to zero OFF = pauses time for sequence every time a reduction in heat load occurs. 29

The following sections 1.8.4.8.8 through 1.8.4.8.10 are intended to provide a basic overview of the PID control algorithm as it applies to the ENVI control. The default PID settings in the ENVI are based on tested application experience with P-K boilers in various hydronic systems. The default settings will be best suited to most P-K boiler applications. Simply put, these values can be interpreted as a timeline: P depends on the present error, I on the accumulation of past errors, and D is a prediction of future errors, based on current rate of change 1.8.4.7.8 Prop band {Proportional band} This parameter in the ENVI is the temperature range in degrees throughout which the logic of the boiler control proportionally modulates the reaction of the boiler to the deviation from setpoint. Proportional band in the ENVI is biased by the adjustment of Derivative time setting. Commonly referred to as the throttling range, proportional band is defined as the amount of change in the controlled variable required to drive the loop output from 0 to 100%. For example: With the proportional band left at the default setting of 20 and a header setpoint of 140 : With the Derivative time set at the default setting of 128 or higher (default setting) the proportional band is below the setpoint (figure 2) If the header temperature drops to130 (10 below SP) The proportional action of the control will be 50%. If the header temperature drops to120 (20 below SP) The proportional action of the control will be 100%. OR: With the proportional band left at the default setting of 20 and a header setpoint of 140 : With the Derivative time set at 0 (and up to 127), the proportional band is symmetrical around the setpoint (figure 1) If the header temperature drops to130 (10 below SP) The proportional action of the control will be 100%. If the header temperature reaches 140 (SP) The proportional action of the control will be 50%. As the header temperature rises above 140 (10 above SP) The proportional action of the control will decrease output to 0% until reaching 10 above setpoint. (50% of proportional band) Figure 1 setpoint Figure 2(default) setpoint Proportional Band Proportional Band 30